Emissions

Air is made up of : s 21%O2 s 78%N s 1% other gasses (mostly argon)

Fuel is primarily made up of : s Hydrocarbons (HC)

Perfect combustion s HC, O2, N2 in s Heat, H2O, CO2 and N2 out

Imperfect combustion s Adds HC, CO, NOx and O2 to exhaust

Stoichiometric s Much of our emissions are related directly to A/F mixtures s Theoretical best A/F ratio for emissions, economy, performance is 14.7:1 s 14.7 pounds of air to 1 pound of fuel

Think about it s Gasoline weighs 6 pounds per gallon s Air weighs 1 pound per 100 gallons s At 15:1 it takes 9000 gallons of air to burn 1 gallon of fuel –9000 Gallons of air is equal to a single car garage

HC - Hydrocarbons s Unburned fuel s Currently measured in parts per million (ppm)

Common causes of high HC s Missfiring will cause HCs –Ignition –Mechanical –Lean s A/f ratios off either way s Timing too advanced –Cools exhaust and cylinder walls

Not so common causes of HC s Quench areas in combustion chamber –Carbon –Poor combustion chamber design s Cam profiles too aggressive

CO - Carbon monoxide s Currently measured in % s EXTREMELY deadly gas!!! s Partially burned fuel s Too much fuel or too little O2 –Combustion process ran out of air s CO directly related to a/f ratios

Causes of high CO s Any thing that will cause a rich fuel mixture –Sensor malfunction –Carburetor or injector failures –Diluted oil s Hard to use as an A/F guide over 15:1 due to flattening out of curve –Must use O2 above stoichiometric

O2 - Oxygen s Currently measured in % s Unused air in exhaust s O2 directly related to A/F s Can also come from dilution –Air pump, exhaust leaks s Missfires will raise O2 s If O2 is > 5% and vehicle running OK then it must be from dilution

CO2 - Carbon dioxide s Currently measured in % s Byproduct of complete combustion s Peak indicates good A/F s Any problems pull CO2 away from peak s Used by Washington State to determine exhaust system integrity

NOx - Oxides of nitrogen s Created when peak combustion temps. exceed 2500F

Causes of high NOx s Advanced timing s Inoperative EGR s Carbon build up s Anything that overheats combustion chamber

Smog, what is it? s Ground level ozone - O3 s Three ingredients; HC, NOx and sunlight s CO is a pollutant all by itself

State emissions testing s Attainment areas vs. non-attainment areas –Ozone and/or CO s Centralized vs. non-centralized testing

ASM test s Loaded test with constant load with a CVS s Idle test s With or without an evaporative emissions test s Test all three gasses

Washington State test s Variation of a ASM test s Loaded cruise test except special vehicles s Idle test s No NOx measuring in effect yet

IM240 test s Varying load test with a constant volume sampler s Idle test s Evaporative emissions test s Testing all three gases s Visual inspection

Remote sensing devices s Like photo radar s Used in California / Colorado

Emission Controls

PCV systems

Purpose of PCV s Control of blowbye gasses (HC) s Reducing moisture and acids extending oil life

PCV history s Road draft tube was responsible for % of vehicles emissions s Completely sealed systems on all domestics since 1968

Components of PCV s Breather to filter incoming air s PCV valve –Calibrated vacuum leak to intake manifold –Controls flow rates based on strength of vacuum –Eliminates backfiring path to crankcase s Bleed orifice type / dual bleed type

PCV system problems s Can flow up to 20% of the total a/f mixture at idle s Plugged system could cause high CO at idle s Stuck open valve could cause lean or high idle speed

PCV system diagnosis / testing s Valve should snap back at idle s Rattle test s Cheap valves pass both tests but could flow wrong s Inspect breathers for plugging s Oil dilution –1% Change = too much dilution or blowbye

Inspect / replace at tune up intervals

Evaporative emissions system

Evap system purpose s To control HC during fuel evaporation

Evap system components s Gas cap –Important seal of system –Easily over looked –Allows air in but pressure out only if >1 psi s Vapor liquid separator

Evap system components s Canister –Stores evaporating vapors –Approx. 1.5 Lbs. Activated charcoal –Can hold twice it’s own weight in fuel –Chrysler used the crankcase in 1971 s Vapor line(s) from tank(s) s Carb bowl venting –Electronic solenoids –Switching with purge valve

Evap system operation (purging) s Uses stored fuel vapors in canister s Variable type-hose to air cleaner snorkel s Constant purge type-vacuum to manifold –Uses TVS and orifice

Evap system operation (purging) s Demand system –None at idle –Uses ported vacuum as control –Manifold vacuum does purging –Needs TVS s Computer controls s OBDII diagnostics

Evap system problems s Failed purge valves / diaphragms rupturing s Plugged filters s Failing TVS can cause cold flooding s Loaded canister due to over full tanks s Charcoal in carb. bowl indicates defective canister

Early fuel evaporation systems

EFE system purpose s Helps a/f mixture vaporize on cold engine s Provide good cold driveability (cold air too dense and leans out mixture) s Improve cold emissions

EFE system purpose s Warms intake to prevent condensation of fuel s Prevents icing in carbs (temps can drop 66f when fuel vaporizes)

Four types of EFE s 1. T.A.C. (thermostatic air cleaner) s 2. EFE grid s 3. Coolant heated intakes and throttle bodies s 4. Heat riser valve

T.A.C. components s Mode door –Cold air position for warm eng. –Warm air position for cold eng. s Uses manifold vacuum and vacuum motor to move mode door s Heat stove and pipe –Primary failure of emission tests

T.A.C. components s Sensor –Bleeds off vacuum at f –Must bleed off vacuum - can not trap it s Wax bulb type s Manual movement (older asians)

T.A.C. problems s Stuck in hot air position will cause ping / NOx –Often caused by a plugged bleed off hole s Any missing piece can cause cold driveability problems s Cracked manifold sucks exhaust into air cleaner

EFE grid components s Electrical heater –Usually only, on carburetors and only on primary bore(s) s Commonly ceramic

EFE grid operation s Heats and mixes a/f mixture s Controlled by switches or relay –Usually powered up cold only

EFE grid problems s Grids melt s Switches stick on s Heater element opens

Coolant passages s Primarily icing controls s Also helps warm intakes

Heat riser valve purpose s Directs exhaust to underside of intake manifold s Prevents condensation s Improves vaporization s Not necessary on PFI engines

Heat riser valve components s Vacuum with rod –Uses TVS s Bimetal spring s On V engines valve will plug off one side of exhaust when cold

Heat riser problems s Binding on shaft s Stuck in cold mode causing ping and NOx by overheating incoming a/f mixture s Valve disintegrating

Air systems purpose s To pump or allow air to be sucked into exhaust system –Completes combustion –Dilutes exhaust gasses –Gives O2 to cats –Heats O2 sensor

Two types - air pump and air suction (pulseair)

Air pump system

Air pump s Belt driven vane and rotor pump s Some use electric air pumps s Some means of filtered air intake –Often using a centrifugal filter s 1/2 Hp draw on engine

Diverter and gulp valves s Purpose: divert AIR away from exhaust on decel to prevent backfire s Gulp dumps AIR to intake –Similar to a decel valve / mixture control valve s Vacuum or electric controlled

Check valve s Purpose: to prevent exhaust from coming up into AIR system s Failed valves can cause melted hoses and diverter valves

Air manifolds and pipes s Rotting out causing backfire / exhaust leaks

Air on CCC cars s Computer controls routing of AIR system s Upstream cold vs. downstream warm s Still diverts totally away during decel

Pulseair system s No pump s Uses negative exhaust pulses s Reed valves s Can still divert or block off AIR s Can be computer controlled s Often mounted to air cleaner

Pulseair system problems s Back firing on decel if reed valves leak s Melted stuff is melted if valves leak s Can stick upstream

EGR systems

Purpose : flows exhaust gas into intake to lower combustion temps which lowers NOx

EGR details s Exhaust supports no combustion s Dilutes a/f mix and slows combustion slightly s First used on Buicks in 1972, common in 1973 s Does not affect a/f ratios

Three methods to obtain EGR s Floor jets –Egr at all times s Cam grinds –Egr at all times s Egr valves

Control of EGR needed for three reasons s Idle; can not support dilution and little NOx s Cold; poor driveability, no NOx, not all engines s WOT; limits power and less NOx due to richer a/f

EGR valve is a means of controlling EGR flow s Basic systems use ported vacuum to control and limit operation and a TVS to eliminate cold operation s Some use a vacuum amplifier –Works like vacuum relay s Often will have delay orifices and valves

Backpressure Transducer s Limits with exhaust pressures s Exhaust pressures good load indicator s Can modulate valve s Many valves have built in transducers –Positive valves vs. Negative valves

Electronic controls s Can use vsv’s to control EGR via ECU s Electric valves –Using solenoids to control operation s Sensors –Position (EVP) –Exhaust pressure (PFE) –Temperature switch

Problems s Inop valves cause high combustion temps = pinging =NOx s Plugged EGR passages common s Too much EGR = lack of power, surge s Stuck open at idle causes rough idle due to excessive dilution

EGR testing s Egr movement under load –Some need to see VSS input s Vacuum present at valve s Lift up at idle to check passages

Catalytic converters

Two types of converters s Oxidizing s Reducing s May be in one case

Oxidizing s First in 1975 s Converts HC and CO to H2O, CO2 and heat s Uses precious metals platinum and palladium

Monolith construction (honeycomb) s Ceramic coated with p&p s Lots of surface area s Very brittle s Most common

Pellet construction s Aluminum oxide pellets coated with p&p s Not as much surface area s Very heavy s Not easily damaged

Oxidizing operation s Needs O2 to convert HC and CO to H2O AND CO2 –Gets O2 from lean a/f ratios, AIR systems, missfires s Light off at 500f, average temps 1400f inside, 700f outside s Abbreviated OC

Reducing cat s Converts NOX into N2, CO2, O2 s Needs lack of oxygen and some CO to work –Likes richer mix –Missfires provide too much o2 s Uses rhodium

Three way or dual bed

First part or bed reducing s Gives off O2 to help second bed s Needs CO which second bed eliminates

Second part oxidizing bed s Uses O2 from first part s Can use air into cat behind first bed

Needs to be close to stoichiometric to work s Only found on cars with closed loop fuel

Problems and testing all types s Plugging –Abuse –If not abuse must find cause before replacing u Rich u Leaded fuel u Missfire u Air system

s Symptoms: s Vacuum not always accurate s Back pressure reading of > 3psi is excessive s Test at back pressure transducer, O2 sensor, AIR fitting, EGR

Efficiency loss s Symptoms: s Loss can be due to lead, coolant, oil, miles s Aftermarket not as effective s DO NOT USE USED CATS s OBDII efficiency monitor

Efficiency testing s Temps f increase across cat s Intrusive method –Egr, AIR pipes (must seal), drilling hole –Need thin probe –Rivet holes up –Not at O2 sensor

Using the bible sticker underhood to id components